A novel flux charging method and a crucible quenching method were employed to study the mechanism of solid fluxes refining method regarding the removal of oxide inclusions (Al₂O₃) from molten aluminum. Electrochemical polishing method was adopted to prepare surfaces of the samples. Through experiments, the morphology of the residual solidified flux in the solidified samples as well as the wetting action of the molten flux during refining were observed for the first time. Three wetting regimes denoted by absorbing regime, engulfing regime and penetration regime correlating with the removal of oxide films (the most typical and common oxide inclusions in molten aluminum) were proposed in terms of different types and distributions of oxide films and different size ratios of the molten flux to oxide films. Particularly, from a thermodynamic point of view, for the first time, the penetration regime provided concrete evidence that the practical oxide inclusions can be wet by molten flux under ambient fluid of molten aluminum. A spreading model was proposed, according to which ingredients and size parameters of practical solid fluxes can be optimized.

Aluminium secondary materials are often contaminated by impurities such as iron. As the alloy properties are affected by impurities, it is necessary to refine aluminium melts. The formation of Fe intermetallics in aluminium melts can be used to develop a purification technology based on the removal of intermetallic compounds. In this study, the temperature range for effective separation of intermetallics was determined in an industrial-relevant Al–Si–Fe–Mn system with 6 to 10 Si wt. %, 0.5 to 2.0 Fe wt. %, and 0 to 2.0 Mn wt. %. Based on DTA (Differential Thermal Analysis) and SEM (scanning electron microscope) results and following the rules of phase boundary drawing, isopleths were drawn. This method allows to derive the temperature ranges of intermetallic phase stability and can be applied for the assessment of melt-refining parameters.

Utilizing titanium diboride (TiB₂) inoculation for grain-refining purposes is a widely established practice in aluminum casthouses and foundries. Since this inoculation is usually implemented jointly with or between routine melt treatment steps ahead of casting, it is important to know whether and how other melt treatment processes affect the fade of TiB₂ particles. For the present study, we investigated the influence of degassing process on the separation behavior of TiB₂ particles in aluminum melt. Multiple sampling methods were employed and the samples were analyzed via spectrometer analysis. The removal efficiency of TiB₂ during the gas-purging process of 5083 aluminum melt was confirmed to be significant over 10 min of treatment time. The rate at which the TiB₂ content decays was found to increase with the impeller rotary speed from 400 rounds per minute (rpm) to 700 rpm. The separation rate of TiB₂ particles was obtained to be 0.05–0.08 min⁻¹ by fitting the experimental data. Particle mapping results suggest that the TiB₂ particles were separated to a dross layer. The obtained experimental results were used to quantitatively evaluate the conventional deterministic flotation model. The deviation between the conventional model and the experimental data was explained through the entrainment–entrapment (EE) model. Suggestions were made for future analytical and experimental works which may validate the EE model.